Wall reported that rats with lesions of the spinal cord at the thoracic level leaving only the dorsal columns intact exhibited severe deficits in tactile sensitivity on the hind legs. The purpose of the proposed research is (1) to confirm and extend Walls's basic finding, using more systematic behavioral sensory discrimination tasks, and (2) to compare the response properties of single units in the somatosensory cortex in intact preparations and in preparations with spinal cord lesions sparing only the dorsal columns. The electrophysiologic and behavioral results will also be compared with those obtained from cats with lesions limited to the dorsal columns.